Align CPS health coverage anchors with at-interview rule inputs

[daphnehanse11]

Closes #629

Summary

• import CPS NOW_* current-coverage flags as reported health coverage fields and emit the corresponding has_*_health_coverage_at_interview rule inputs needed by policyengine-us
• keep compatibility aliases for existing Marketplace and ESI inputs while adding current-coverage detail used for ACA and Medicaid reconciliation
• anchor ACA takeup to has_marketplace_health_coverage_at_interview and Medicaid takeup to has_medicaid_health_coverage_at_interview in CPS construction, local-area publishing, and unified calibration
• add dataset test coverage that distinguishes Medicaid-specific coverage from broader means-tested coverage

Testing

• uv run pytest policyengine_us_data/tests/test_datasets/test_cps.py policyengine_us_data/tests/test_stochastic_variables.py policyengine_us_data/tests/test_calibration/test_unified_calibration.py -q
• uv run make format